Field evaluation of novel plant‐derived porcine circovirus type 2 vaccine related to subclinical infection

BACKGROUND: The objective of this field trial was to evaluate the efficacy of a new plant‐based porcine circovirus type 2a (PCV2a) vaccine. This vaccine was a recombinant capsid subunit PCV2a vaccine based on the Nicotiana benthamiana expression system. METHODS: Three farms were selected for the study based on their history of subclinical PCV2 infection. A total of 40 18‐day‐old pigs were randomly allocated to either vaccinated or unvaccinated groups (20 pigs per group; 10 = male and 10 = female). Pigs received a 2.0‐mL dose of the plant‐based PCV2a vaccine intramuscularly at 21 days of age in accordance with the manufacturer's recommendations, whereas unvaccinated pigs were administered a single dose of phosphate buffered‐saline at the same age. RESULTS: Vaccination had a positive effect on pig growth performance compared to that of unvaccinated pigs on all three of the farms. Vaccination of pigs with a plant‐based PCV2a vaccine induced high levels of neutralizing antibodies titres against PCV2d and PCV2d‐specific interferon‐γ secreting cells which resulted in the reduction of PCV2d viral load and reduced lymphoid lesions severity. CONCLUSIONS: The results of this field trial demonstrated cross‐protection of PCV2d by a plant‐based PCV2a vaccine and a positive effect of pig growth performance with vaccination.